Various kinds of contact lenses have been developed for applying visual corrections to the human eye. Some of the types of contact lenses which are presently available commercially have been mentioned hereinabove.
It is known, for example, that hard contact lenses are made of polymethylmethacrylate materials. Proper care of such lenses, for example, had included storing the same in specially developed cleaning and storage solutions to maintain them in suitable condition when not in use. The storage solutions are furthermore generally used to sterilize the lenses during storage. When ready for use, hard contact lenses are immersed into wetting solutions designed to condition and prepare the same for wetting by natural tear fluids in order to make the wearing of the contact lenses more tolerable by reducing irritation of the eye. Prior art contact lens wetting solutions have frequently contained polyvinyl alcohol as a wetting agent.
Another type of contact lens which has been developed is the gas-permeable cellulose acetate butyrate lens. Lenses of this type are somewhat more flexible than the hard polymethylmethacrylate lenses, but are less flexible than the well-known soft lenses. Cellulose acetate butyrate lenses are based on organic cellulose esters produced by a reaction between cellulose and the appropriate acid and anhydrides in the presence of a suitable catalyst. For example, cellulose acetate may be esterified with a mixture of butyric acid, acidic anhydride, and concentrated sulfuric acid catalyst.
The development of flexible lenses has been generally considered in two broad categories, namely, hydrophilic and hydrophobic lenses. Hydrophobic contact lenses are usually based on elastic and flexible silicone rubber (polysiloxane) and are generally made of cross-linked dimethyl polysiloxane. A typical lens of this type is disclosed in U.S. Pat. No. 3,228,741. Hydrophilic soft contact lenses include hydrated gel lenses, which can be prepared, for example, by copolymerizing hydrophilic, organic monomers having an olefinic double bond with a small amount of cross-linking agents usually having two polymerizable olefinic double bonds. These lenses may usually be based on polyhydroxylated alkyl methacrylates cross-linked, for example, with a hydroxyethyl dimethacrylate. Hydrated gel lenses may, for example, include hydroxyethyl methacrylate or its analogs, ethylene-glycol dimethacrylate or its analog, polymethylmethacrylate or its analog, polyvinyl pyrrolidone, and so forth. Hydrated gel lenses are disclosed, for example, in U.S. Pat. Nos. 3,220,960; 3,361,858; and 3,499,862.
Silicone and silicone derivative lenses may for example be prepared of hydroxy dimethyl silane. This type of lens and the other lenses mentioned above as well as various other types of lenses which have been developed are all cleanable and wettable by the compositions set forth herein as will be discussed in greater detail hereinbelow. As will also be shown below, the elements of the composition of the invention synergistically cooperate with one another in a manner not known in the prior art, which is exemplified in a broad collection of patents including but not limited to U.S. Pat. Nos. 2,386,106; 3,240,709; 3,431,343; 3,882,036; 3,888,782; 3,954,644; 4,046,706; 4,013,576; 4,104,187; and 4,127,423.
In U.S. Pat. No. 2,386,106, Wilmer Gangloff discloses a detergent for cleaning hard, polished glass surfaces. This patent discloses that a dihydric alcohol, 2-methyl-2,4-pentane diol when added to water in varying percentages, not only lowers the surface tension of water but provides a detergent composition which is sutable for cleaning hard, polished glass surfaces.
Billy Rankin discloses in U.S. Pat. No. 3,240,709 a cleaning composition for contact lenses and like ophthalmic apparatus. This patentee more particularly discloses a cleaning composition comprised of wetting agents which readily dissolve crystalline tear deposits without harming the contact lens ingredients. The cleaning composition disclosed is buffered to the pH range of the human tear. A principal ingredient of the cleansing solution is methylcellulose which is of 4,000 centipoises which has a good ability to lower the surface tension and is non-reactant with conventional ophthalmic buffering agents.
Herbert Stecker in U.S. Pat. No. 3,431,343 discloses a method of obtaining germicidal and fungicidal activities by contacting microorganisms with an effective concentration of a compound having the general formula: ##STR1## wherein: X is a halogen atom of the class consisting of chlorine and fluorine; Y is a member of the class consisting of hydrogen, methyl, bromine and chlorine; and n is a numeral from 0 to 3.
Examples of the Stecker composition include: 2,2'-trifluoromethyl-methylene-bisphenol; 2,2'-dichloromonofluoromethyl methylene-bisphenol; 2,2'-difluoromono-chloro-bis (4,6-dichlorophenol); 2,2'-trifluoromethyl-methylene-bis (3,4,6-trichlorophenol); and 2,2'-trifluoromethyl-methylene-bis (4,6-chloro-5-methyl phenol).
In U.S. Pat. No. 3,882,036 is disclosed a contact lens cleaning, storing, and wetting solution especially adapted for flexible silicone contact lenses. The solution comprises a poly-(oxyethylene)-poly(oxypropylene) block copolymer having a molecular weight between about 1,900 and 15,500, a water solubility in excess of about 10 grams per 100 ml., a cloud point in 1% aqueous solution above about 30.degree. C., a microbial growth inhibitor, purified water, and a neutral water-soluble compatible salt to provide a specified salt content. The patentees Joseph Krezanoski et al further disclose that the solution can contain disodium or trisodium ethylene-diamine, tetraacetate and a polymeric viscosity building agent.
M. Boghosian, in U.S. Pat. No. 3,888,782, discloses an aqueous substantially isotonic cleaning and sterilizing solution for plastic hydrophilic soft contact lenses including chlorhexidine and polyvinylpyrrolidone. It is alleged that the sterilizing solution is non-toxic to the eye of the wearer and in the presence of a suitable amount of water-soluble polyhydroxyethylmethacrylate prevents the build-up of opaque deposits on the surface of soft contact lenses.
J. Krezanoski et al make a further disclosure of a contact lens cleaning, storing and wetting solution in U.S. Pat. No. 3,954,644.
J. Krezanoski, in U.S. Pat. No. 4,046,706 discloses a composition for cleaning contact lenses which comprises poly(oxyethylene)-poly(oxypropylene) block copolymer having a molecular weight as mentioned hereinabove with other characteristics corresponding to the previously indicated Krezanoski patents.
S. Loshaek discloses in U.S. Pat. No. 4,013,576 a contact lens treating composition resulting from the incorporation of an amphoteric surfactant as a detergent, which provides good cleaning properties with no eye irritation and is stable in the presence of positively charged bacteriocides in the composition.
Murray Sibley et al disclose in U.S. Pat. No. 4,104,187 methods and compositions for the elevated temperature disinfection of soft contact lenses. Attention is called, by way of example, to the use of an aqueous stabilized saline solution having a small amount of non-irritating neutral surfactants. It is pointed out that a particularly effective surfactant is N-hydroxyalkylated fatty acid amides.
In U.S. Pat. No. 4,127,423, Billy Rankin discloses that silicone and hydrophilic soft contact lenses may be freed of proteinaceous deposits and other deposits by rubbing them with an aqueous solution of a crystalline sodium silicate having a pH of 10.2-10.9 and rinsing the same. It is pointed out that the solution may contain, in addition, sodium chloride in isotonic amounts, viscosity agents, wetting agents, detergents and bacteriocides.
While some of the patents suggest various features in common with the disclosure to follow hereinafter, it will become obvious that the above patents do not disclose certain of the elements to be mentioned hereinbelow nor the synergistic effect of such elements in combination with various other constituents of the compositions to be mentioned hereinbelow. It will also become obvious that the compositions and methods disclosed hereinbelow represent a significant advancement in the art of contact lens cleaning.
Examples of antimicrobials/preservatives used either in contact lens solutions or in "ophthalmologicals" include CHLOROBUTANOL which the Merck Index calls "Acetone Chloroform." Its structure is: ##STR2## It is described as an antiseptic and preservative for biological fluids. It is currently used in an anti-glaucoma drug called phospholine iodide, produced by Ayerst. It is not known to have lens cleaning properties.
Finally, in the article "Microbiology of Soft and Hard Contact Lens Care" which comes from Symposium on Flexible Contact Lenses, ed. J. Bitonte and G. Feldman (C. V. Mosby, 1972), pages 211 and 212, it can be seen that under specified test conditions, thimerosal cannot eliminate Staphylococcus aureus (or Micrococcus or Bacillus) even after prolonged soaking. Thimerosal is not very active against "Gram Positive" microorganisms but is very active against "Gram Negative" organisms.